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	$58.66	6.753%	$62.6213	$62.62	$62.60	$62.60
Purchase #2	$145.48	8.821%	$158.3128	$158.31	$158.30	$158.30
Purchase #3	$169.33	6.394%	$180.157	$180.16	$180.15	$180.20
Purchase #4	$41.68	3.595%	$43.1784	$43.18	$43.20	$43.20
Purchase #5	$165.58	8.869%	$180.2653	$180.27	$180.25	$180.30
Purchase #6	$206.54	7.786%	$222.6212	$222.62	$222.60	$222.60
Purchase #7	$239.27	3.784%	$248.324	$248.32	$248.30	$248.30
7 purchase totals =	$1,026.54		$1,095.4800	$1,095.48	$1,095.40	$1,095.50