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	$222.34	4.802%	$233.0168	$233.02	$233.00	$233.00
Purchase #2	$241.92	13.841%	$275.4041	$275.40	$275.40	$275.40
Purchase #3	$81.37	5.401%	$85.7648	$85.76	$85.75	$85.80
Purchase #4	$237.67	5.337%	$250.3544	$250.35	$250.35	$250.40
Purchase #5	$33.94	12.377%	$38.1408	$38.14	$38.15	$38.10
Purchase #6	$149.99	10.522%	$165.7719	$165.77	$165.75	$165.80
Purchase #7	$205.96	6.277%	$218.8881	$218.89	$218.90	$218.90
7 purchase totals =	$1,173.19		$1,267.3409	$1,267.33	$1,267.30	$1,267.40