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	$196.91	4.320%	$205.4165	$205.42	$205.40	$205.40
Purchase #2	$81.60	4.441%	$85.2239	$85.22	$85.20	$85.20
Purchase #3	$73.86	12.174%	$82.8517	$82.85	$82.85	$82.90
Purchase #4	$193.73	5.516%	$204.4161	$204.42	$204.40	$204.40
Purchase #5	$114.31	10.241%	$126.0165	$126.02	$126.00	$126.00
Purchase #6	$175.70	9.181%	$191.831	$191.83	$191.85	$191.80
Purchase #7	$178.62	11.533%	$199.2202	$199.22	$199.20	$199.20
7 purchase totals =	$1,014.73		$1,094.9759	$1,094.98	$1,094.90	$1,094.90