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	$162.60	7.582%	$174.9283	$174.93	$174.95	$174.90
Purchase #2	$93.67	6.739%	$99.9824	$99.98	$100.00	$100.00
Purchase #3	$64.77	12.125%	$72.6234	$72.62	$72.60	$72.60
Purchase #4	$53.37	12.279%	$59.9233	$59.92	$59.90	$59.90
Purchase #5	$112.43	13.559%	$127.6744	$127.67	$127.65	$127.70
Purchase #6	$21.60	3.142%	$22.2787	$22.28	$22.30	$22.30
Purchase #7	$68.29	9.293%	$74.6362	$74.64	$74.65	$74.60
7 purchase totals =	$576.73		$632.0467	$632.04	$632.05	$632.00