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	$103.73	7.408%	$111.4143	$111.41	$111.40	$111.40
Purchase #2	$216.37	4.434%	$225.9638	$225.96	$225.95	$226.00
Purchase #3	$56.67	4.555%	$59.2513	$59.25	$59.25	$59.30
Purchase #4	$52.87	11.621%	$59.014	$59.01	$59.00	$59.00
Purchase #5	$187.73	11.849%	$209.9741	$209.97	$209.95	$210.00
Purchase #6	$231.33	10.188%	$254.8979	$254.90	$254.90	$254.90
Purchase #7	$168.74	3.342%	$174.3793	$174.38	$174.40	$174.40
7 purchase totals =	$1,017.44		$1,094.8947	$1,094.88	$1,094.85	$1,095.00