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	$191.63	4.780%	$200.7899	$200.79	$200.80	$200.80
Purchase #2	$25.51	10.474%	$28.1819	$28.18	$28.20	$28.20
Purchase #3	$44.83	6.692%	$47.83	$47.83	$47.85	$47.80
Purchase #4	$221.48	7.532%	$238.1619	$238.16	$238.15	$238.20
Purchase #5	$163.55	10.850%	$181.2952	$181.30	$181.30	$181.30
Purchase #6	$136.94	6.177%	$145.3988	$145.40	$145.40	$145.40
Purchase #7	$247.97	6.813%	$264.8642	$264.86	$264.85	$264.90
7 purchase totals =	$1,031.91		$1,106.5219	$1,106.52	$1,106.55	$1,106.60