Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$152.52	10.127%	$167.9657	$167.97	$167.95	$168.00
Purchase #2	$96.33	9.813%	$105.7829	$105.78	$105.80	$105.80
Purchase #3	$146.37	3.663%	$151.7315	$151.73	$151.75	$151.70
Purchase #4	$119.34	5.183%	$125.5254	$125.53	$125.55	$125.50
Purchase #5	$232.93	4.103%	$242.4871	$242.49	$242.50	$242.50
Purchase #6	$157.86	4.779%	$165.4041	$165.40	$165.40	$165.40
Purchase #7	$225.75	5.223%	$237.5409	$237.54	$237.55	$237.50
7 purchase totals =	$1,131.10		$1,196.4376	$1,196.44	$1,196.50	$1,196.40