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	$153.92	7.802%	$165.9288	$165.93	$165.95	$165.90
Purchase #2	$16.75	3.523%	$17.3401	$17.34	$17.35	$17.30
Purchase #3	$250.63	5.607%	$264.6828	$264.68	$264.70	$264.70
Purchase #4	$105.47	3.801%	$109.4789	$109.48	$109.50	$109.50
Purchase #5	$121.60	5.368%	$128.1275	$128.13	$128.15	$128.10
Purchase #6	$212.88	9.810%	$233.7635	$233.76	$233.75	$233.80
Purchase #7	$180.80	10.654%	$200.0624	$200.06	$200.05	$200.10
7 purchase totals =	$1,042.05		$1,119.3840	$1,119.38	$1,119.45	$1,119.40