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	$81.26	4.765%	$85.132	$85.13	$85.15	$85.10
Purchase #2	$59.34	4.277%	$61.878	$61.88	$61.90	$61.90
Purchase #3	$91.89	9.463%	$100.5856	$100.59	$100.60	$100.60
Purchase #4	$220.57	6.742%	$235.4408	$235.44	$235.45	$235.40
Purchase #5	$221.27	12.157%	$248.1698	$248.17	$248.15	$248.20
Purchase #6	$220.39	10.683%	$243.9343	$243.93	$243.95	$243.90
Purchase #7	$236.59	11.820%	$264.5549	$264.55	$264.55	$264.60
7 purchase totals =	$1,131.31		$1,239.6954	$1,239.69	$1,239.75	$1,239.70