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	$90.88	5.589%	$95.9593	$95.96	$95.95	$96.00
Purchase #2	$76.52	11.711%	$85.4813	$85.48	$85.50	$85.50
Purchase #3	$236.34	13.726%	$268.78	$268.78	$268.80	$268.80
Purchase #4	$209.25	10.312%	$230.8279	$230.83	$230.85	$230.80
Purchase #5	$87.29	11.254%	$97.1136	$97.11	$97.10	$97.10
Purchase #6	$139.64	4.134%	$145.4127	$145.41	$145.40	$145.40
Purchase #7	$134.98	5.148%	$141.9288	$141.93	$141.95	$141.90
7 purchase totals =	$974.90		$1,065.5036	$1,065.50	$1,065.55	$1,065.50