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	$88.76	6.180%	$94.2454	$94.25	$94.25	$94.20
Purchase #2	$85.60	5.842%	$90.6008	$90.60	$90.60	$90.60
Purchase #3	$218.35	13.857%	$248.6068	$248.61	$248.60	$248.60
Purchase #4	$222.58	11.676%	$248.5684	$248.57	$248.55	$248.60
Purchase #5	$108.62	5.485%	$114.5778	$114.58	$114.60	$114.60
Purchase #6	$170.63	6.215%	$181.2347	$181.23	$181.25	$181.20
Purchase #7	$118.47	6.673%	$126.3755	$126.38	$126.40	$126.40
7 purchase totals =	$1,013.01		$1,104.2094	$1,104.22	$1,104.25	$1,104.20