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	$181.52	3.790%	$188.3996	$188.40	$188.40	$188.40
Purchase #2	$25.64	11.277%	$28.5314	$28.53	$28.55	$28.50
Purchase #3	$68.69	5.792%	$72.6685	$72.67	$72.65	$72.70
Purchase #4	$235.34	9.165%	$256.9089	$256.91	$256.90	$256.90
Purchase #5	$42.82	12.379%	$48.1207	$48.12	$48.10	$48.10
Purchase #6	$219.48	9.723%	$240.82	$240.82	$240.80	$240.80
Purchase #7	$174.61	3.709%	$181.0863	$181.09	$181.10	$181.10
7 purchase totals =	$948.10		$1,016.5354	$1,016.54	$1,016.50	$1,016.50