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	$93.71	9.107%	$102.2442	$102.24	$102.25	$102.20
Purchase #2	$144.33	4.180%	$150.363	$150.36	$150.35	$150.40
Purchase #3	$59.37	13.123%	$67.1611	$67.16	$67.15	$67.20
Purchase #4	$87.73	8.747%	$95.4037	$95.40	$95.40	$95.40
Purchase #5	$54.74	9.231%	$59.793	$59.79	$59.80	$59.80
Purchase #6	$189.26	3.363%	$195.6248	$195.62	$195.60	$195.60
Purchase #7	$172.27	11.389%	$191.8898	$191.89	$191.90	$191.90
7 purchase totals =	$801.41		$862.4796	$862.46	$862.45	$862.50