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	$93.31	3.216%	$96.3108	$96.31	$96.30	$96.30
Purchase #2	$12.92	10.468%	$14.2725	$14.27	$14.25	$14.30
Purchase #3	$87.80	11.419%	$97.8259	$97.83	$97.85	$97.80
Purchase #4	$41.68	8.637%	$45.2799	$45.28	$45.30	$45.30
Purchase #5	$86.47	4.184%	$90.0879	$90.09	$90.10	$90.10
Purchase #6	$204.89	13.787%	$233.1382	$233.14	$233.15	$233.10
Purchase #7	$223.33	3.821%	$231.8634	$231.86	$231.85	$231.90
7 purchase totals =	$750.40		$808.7786	$808.78	$808.80	$808.80