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	$53.57	5.749%	$56.6497	$56.65	$56.65	$56.60
Purchase #2	$66.79	12.740%	$75.299	$75.30	$75.30	$75.30
Purchase #3	$42.72	5.298%	$44.9833	$44.98	$45.00	$45.00
Purchase #4	$62.79	8.125%	$67.8917	$67.89	$67.90	$67.90
Purchase #5	$222.98	3.254%	$230.2358	$230.24	$230.25	$230.20
Purchase #6	$52.42	12.753%	$59.1051	$59.11	$59.10	$59.10
Purchase #7	$87.54	4.736%	$91.6859	$91.69	$91.70	$91.70
7 purchase totals =	$588.81		$625.8505	$625.86	$625.90	$625.80